1. Field of the Invention
The present invention relates to an electric pulse generator and a method for making the electric pulse generator. In particular, the present invention relates to an explosive-driven electric pulse generator and a method for making the explosive-driven electric pulse generator.
2. Description of Related Art
High-voltage, electrical pulses are employed for many different uses. For example, such pulses may be used in defense, flash X-ray, oilfield logging, and oilfield radiography applications. While electrical pulses may be generated in many different ways, one way of producing such pulses is by mechanically impacting or shocking a material that exhibits a piezoelectric effect. Generally, these materials have a crystalline structure of non-centrosymmetric unit cells. When a mechanical stress is applied to such a material, an electrical charge is produced. The voltage of the electrical charge produced by mechanically stressing a piezoelectric material is proportional to the amount of mechanical stress applied to the material. Thus, if a high-voltage electrical charge is desired, a correspondingly large mechanical stress is applied to the piezoelectric material.
One way of generating a high-voltage electrical charge with a piezoelectric material is to impact the piezoelectric material with an explosive-driven member or with products (e.g., gases, particles, etc.) generated during detonation of an explosive material. FIGS. 1 and 2 illustrate two conventional apparatuses used to generate electrical pulses. In FIG. 1, an electric pulse generator 101 includes a piezoelectric material 103 disposed between and in electrical contact with a housing 105 and a receiver 107. Housing 105 defines a cavity 109 in which an explosive material 111 is disposed. Upon detonation of explosive material 111, the products of detonation urge piezoelectric material 103 toward receiver 107, mechanically stressing piezoelectric material 103. The electrical charge produced by piezoelectric material 103 is electrically conducted to housing 105 and to receiver 107, where it may be accessed via electrical leads 113, 115.
FIG. 2 depicts a conventional electric pulse generator 201 alternative to that shown in FIG. 1. Elements of electric pulse generator 201 generally correspond to those of electric pulse generator 101 (shown in FIG. 1) except that a projectile 203 is disposed between an explosive material 205 and piezoelectric material 103. Upon detonation of explosive material 205, the products of detonation propel projectile 203 toward and into impact with piezoelectric material 103. Projectile 203 mechanically stresses piezoelectric material 103, producing an electrical charge. The electrical charge is conducted to housing 105 and to receiver 107, where it may be accessed via electrical leads 113, 115.
Such conventional electric pulse generators, however, suffer from several problems. For example, the explosive arrangement may create a pressure pulse on detonation that is too short to sufficiently compress a thicker portion of piezoelectric material. Moreover, the explosive arrangement may produce a large peak pressure during the detonation pressure pulse, resulting in premature breakdown of the piezoelectric material. In either case, the resulting electrical pulse may exhibit a lower voltage than desired.
Further, typical conventional electric pulse generators comprise a relatively large portion of explosive material. Such electric pulse generators, therefore, must be handled carefully to avoid inadvertent detonation of the explosive material.
While there are many ways known in the art to produce a high-voltage electrical pulse, considerable room for improvement remains. The present invention is directed to overcoming, or at least reducing, the effects of one or more of the problems set forth above.